Which equation has (2, - 1) as a solution?

A) y = 2x - 1

B) y = x + 3

C) y = x - 3

D) y = - 2x + 1

(Remember - 1 is the y coordinate and 2 is the x coordinate)

To find which of the following equations has (2, - 1) as a solution, we just need to substitute the x and y values shown in the ordered pair into the equation, and if it simplifies into a true statement, then it will be a solution.

A) y = 2x - 1

-1 = 2 (2) - 1

-1 = 4 - 1

-1 = 3

Except, - 1 ≠ 3, so the answer isn't A.

B) y = x + 3

-1 = 2 + 3

-1 = 5

Except, - 1 ≠ 5, so the answer isn't B either.

C) y = x - 3

-1 = 2-3

-1 = - 1

-1 does equal - 1, so the answer is C.

Just to be sure, we should make sure that answer D doesn't work either.

D) y = - 2x + 1

-1 = - 2 (2) + 1

-1 = - 4 + 1

-1 = - 3

-1 doesn't equal - 3, so D isn't the answer.

Therefore, the equation that has (2, - 1) as a solution is C) y = x - 3.